The forces loyal to President President Bashar al-Assad of Syria entered Afrin last week to support the People’s Protection Units, the Kurdish militia known as Y.P.G. that is the stated target of the operation Turkey and allied Syrian rebel fighters began in January.

The Syrian Observatory for Human Rights, a monitoring group based in Britain, said the airstrike, which hit a camp in Kafr Jina, was the third time in 48 hours that Turkish warplanes had struck pro-government forces in Afrin.

The Syrian Democratic Forces, a Kurdish-led, United States-backed alliance, said in a statement that Turkish airstrikes had targeted positions held by the Syrian Army’s “popular forces” from 5 a.m. to 10 a.m.

It did not specify a location and did not give a death toll.

Prime Minister Binali Yildirim of Turkey said his country’s forces had captured the town of Rajo from militants. The monitoring group said the Turkish Army was in control of about 70 percent of the town, 16 miles northwest of the city of Afrin.

The Syrian Democratic Forces statement said that a group of Turkish forces and allied Syrian factions had infiltrated Rajo, and that clashes were continuing there.

Syria is now considering shooting down Turk war planes over its territorial air space.

Russia is in consultation with the Syrian government as to the full-scale-war implications of taking such action, but the Syria government is insisting this is needed.